During their service life gearboxes for industrial applications or wind power plants are exposed to a dynamic load sequence of torques and bending moments as well as axial and radial forces. Load spectra defined by users are used to design gearboxes. Actual loads that differ from these load spectra can shorten useful life and interrupt processing, manufacturing or energy generation processes. It is therefore important to detect the loads that actually occur in gearboxes in particular for operation regulation and machine design.
A method for measuring torque in a gearbox with a number of elongation sensors fastened in each instance to a diaphragm of a flexible external gearwheel is known from DE 103 21 210 A1, in which method a gain of output signals from the elongation sensors is increased in each instance before the output signals are combined to form a resulting measurement signal. Adjustment of the gain of the output signals from the elongation sensors allows compensation for rotational ripple contained in the output signals.
GB 2 385 425 A discloses a method for measuring torque in a gearbox, in which a contactless rotation angle sensor is arranged at both ends of a gear shaft and interacts with an assigned detector unit. The detector units here are each mounted on a housing wall or cover. The two detector units are used to derive a phase difference signal, which is a measure of a load-dependent torsion of the gear shaft. A torque acting on the gear shaft is determined from a known torsional stiffness of the gear shaft and the measured torsion.
A measuring device for detecting an overload moment occurring in a gearbox is known from DE 38 04 389 A1, where a measuring device is arranged in the interior of a drive shaft and comprises an optical transmitter, a reflecting mirror and a photoelectric receiver. In the event of overload, the drive shaft bends in such a manner that a reflecting mirror arranged orthogonally to the shaft axis deflects a laser beam emitted by the optical transmitter. The deflected reflection beam produces an electronic signal at the photoelectric receiver, triggering overload protection.
WO 2011/012497 A9 discloses a gearbox, the drive shaft or output shaft of which has a magnetically or optically encoded segment in a region of a housing opening. Its encoding can be changed by an action of a torque or force on the drive shaft or output shaft. A sensing device is used for the contactless detection of the magnetic or optical encoding of the drive shaft or output shaft. The sensing device is arranged in a housing cover enclosing the magnetically or optically encoded segment of the drive shaft or output shaft and is connected electrically to an evaluation device for detecting a load spectrum.